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Exact Solutions and Scalar Fields in Gravity - Instituto Avanzado de ...

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Quantum cosmology with self–<strong>in</strong>teract<strong>in</strong>g scalar field 201<br />

3.1. EXACT SOLUTIONS FOR BIANCHI I<br />

WITH<br />

For Bianchi type I cosmological mo<strong>de</strong>l We restrict ourselves<br />

to the case i.e. this potential<br />

has been used <strong>in</strong> classical Bianchi type I vacuum cosmology [10] <strong>and</strong> for<br />

isotropic mo<strong>de</strong>ls with a barotropic fluid[11]; this potential is one of those<br />

that could produce <strong>in</strong>flation[4]. This choice simplifies the WDW equation<br />

<strong>and</strong> allows us to obta<strong>in</strong> exact solutions,<br />

where <strong>and</strong> the are constants.<br />

The follow<strong>in</strong>g wavefunction can be obta<strong>in</strong>ed by superposition or it can<br />

be substituted <strong>in</strong>to the WDW equation to check that it is a particular<br />

solution<br />

where r is an arbitrary real number; satisfy the relations<br />

For a<br />

wormhole Tak<strong>in</strong>g the negative root for we can check that<br />

the wavefunction is exponentially damped for large spatial geometry,<br />

i.e., when <strong>and</strong> also that it does not oscillate when<br />

3.2. SOLUTIONS FOR BIANCHI I WITH<br />

ANOTHER POTENTIAL<br />

We take another potential for which it is possible to obta<strong>in</strong> exact<br />

solutions to WDW equation. In Eq.(26) if we take the<br />

action becomes,<br />

We change variables <strong>and</strong> take a potential,<br />

The correspond<strong>in</strong>g WDW equation is given by

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